DTC B1280: Left Side Junction Block ECU Communication Stop: Procedure

1. Remove the MPX-B fuse from the engine room relay block No. 1.
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   MPX-B fuse	Always	Below 1 Ω

NG → REPLACE FUSE (MPX-B) 

OK: Go to next step 

1. Disconnect the LD connector.
   Fig 1: LD Connector

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the voltage and resistance according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   LD-18 (MPXB) - Body ground	Always	11 to 14 V

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   LD-3 (GND) - Body ground	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (COWL SIDE JUNCTION BLOCK LH - BATTERY AND BODY GROUND) 

OK: Go to next step 

1. Disconnect the Q3, A30, M18 and 2F connectors.
   Fig 2: Q3, A30, M18 And 2F Connectors

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   Q3-15 (MPX1) - M18-3 (MPX1)	Always	Below 1 Ω
   A30-17 (MPX2) - 2F-6 (MPX2)	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → REPLACE MAIN BODY ECU LH (COWL SIDE JUNCTION BLOCK LH)